1. Technical Field to which the Invention Pertains
The present invention relates to a chemical vapor deposition apparatus for batch processing a plurality of substrates and a film deposition method using the same.
2. Prior Art
A chemical vapor deposition (CVD) apparatus allows the formation of thin films such as a semiconductor film, a metal film, and an insulating film with high controllability and is therefore indispensable to a fabrication process for a semiconductor device.
FIG. 4 is a cross-sectional view showing a structure of a conventional chemical vapor deposition apparatus. The apparatus shown herein is a metal organic chemical vapor deposition (MOCVD) apparatus for growing a semiconductor layer by using, in particular, a metal organic compound and a reactive gas as raw materials.
As shown in FIG. 4, in the conventional MOCVD apparatus, a gas mixture (raw material gas) of an organic metal compound, phosphine (PH3), arsine (AsH3), and the like is introduced into a vacuum processing chamber 104 from a raw-material-gas inlet pipe 106. Since substrates 103 each fixed to a tray 112 in a susceptor 102 with one principal surface thereof facing downward have been heated by using heaters 111, the raw material gas introduced into the vacuum processing chamber 104 undergoes a thermo-chemical reaction on the downwardly facing principal surface of each of the substrates 103. This causes the deposition of a thin film made of a semiconductor or the like.
When a flow of the raw material gas directed toward one of exhaust pipes 108 is disturbed, a reaction product adheres in the form of particles (particulates) to the substrates 103. To prevent the adhesion of the particles, the conventional MOCVD apparatus supplies a barrier gas from the upper center portion of the vacuum processing chamber 104. The barrier gas has its flow rate controlled by using a single MFC (mass flow controller) and is branched in the upper center region of the vacuum processing chamber 104 to be supplied to the center portion and outer peripheral portion thereof The barrier gas supplied to the center portion flows between the heaters 111 and the susceptor 102 to be exhausted from the exhaust pipes 108, while the barrier gas supplied to the outer peripheral portion flows over the heaters 111 to be exhausted from the exhaust pipes 108.
As examples of a barrier gas supply method, there have also been a method which supplies a barrier gas from a center pipe composed of multiple pipes (see, e.g., Japanese Laid-Open Patent Publication No. HEI 9-246192) and a method which supplies an inert gas along the side surfaces of the vacuum processing chamber 104 (see, e.g., Japanese Laid-Open Patent Publication No. HEI 7-122507).